Lattice renormalisation of O(a) improved heavy-light operators: an addendum

The analytical expressions and the numerical values of the renormalisation constants of dimension 3 static-light currents are given at one-loop order of perturbation theory in the framework of Heavy Quark Effective Theory and with an improved gauge action: the static quark is described by the HYP-smeared action and the light quark is of Wilson kind. This completes a work started few years ago and is actually an intermediate step in the measurement of the decay constants $f_{B}$ and $f_{B_{s}}$ by the European Twisted Mass Collaboration [arXiv:1107.1441[hep-lat]].Comment: 5 pages, no figure

Density distributions in the BB meson

We report on a two-flavor lattice QCD study of the axial, charge and matter distributions of the $B$ meson and its first radial excitation. As our framework is the static limit of Heavy Quark Effective Theory (HQET), taking their Fourier transform gives access to several form factors at the kinematical point $q^2=0$. Moreover they provide some useful information on the nature of an excited state, i.e. a radial excitation of a quark-antiquark bound state or a multihadron state.Comment: 26 pages, 25 figures, 12 tables; published versio

Pion couplings to the scalar B meson

We present two-flavor lattice QCD estimates of the hadronic couplings $g_{B^*_0 B \pi}$ and $g_{B_1^* B_0^* \pi}$ that parametrise the non leptonic decays $B^*_0 \to B \pi$ and $B^*_1 \to B_0^* \pi$. We use CLS two-flavour gauge ensembles. Our framework is the Heavy Quark Effective Theory (HQET) in the static limit and solving a Generalized Eigenvalue Problem (GEVP) reveals crucial to disentangle the $B^*_0$($B^*_1$) state from the $B \pi$($B^*\pi$) state. This work brings us some experience on how to treat the possible contribution from multihadronic states to correlation functions calculated on the lattice, especially when $S$-wave states are involved.Comment: 12 pages, 10 figures, published versio

Lattice renormalisation of O(a) improved heavy-light operators

The analytical expressions and the numerical values of the renormalisation constants of ${\cal O}(a)$ improved static-light currents are given at one-loop order of perturbation theory in the framework of Heavy Quark Effective Theory: the static quark is described by the HYP action and the light quark is described either with the Clover or the Neuberger action. These factors are relevant to extract from a lattice computation the decay constants $f_B$, $f_{B_S}$ and the set of bag parameters $B_i$ associated with $B-\bar{B}$ mixing phenomenology in the Standard Model and beyond.Comment: 16 pages, 2 figures, 4 tables; few comments and references added; version to be published in Phys Rev

Renormalization of quark propagator, vertex functions and twist-2 operators from twisted-mass lattice QCD at NfN_f=4

We present a precise non-perturbative determination of the renormalization constants in the mass independent RI'-MOM scheme. The lattice implementation uses the Iwasaki gauge action and four degenerate dynamical twisted mass fermions. The gauge configurations are provided by the ETM Collaboration. Renormalization constants for scalar, pseudo-scalar, vector and axial operators, as well as the quark propagator renormalization, are computed at three different values of the lattice spacing, two volumes and several twisted mass parameters. The method we developed allows for a precise cross-check of the running, thanks to the particular proper treatment of hypercubic artifacts. Results for the twist-2 operator $O_{44}$ are also presented.Comment: 20 pages, 20 figures, submitted to Phys. Rev.

The distribution amplitude of the ηc\eta_c meson

We report on the first lattice determination of the pseudoscalar meson $\eta_c$ light-cone distribution amplitude, using a set of three CLS $N_f=2$ ensembles at a pion mass $m_{\pi} \sim 270~\text{MeV}$ and lattice spacings $a \sim 0.076~\text{fm}$, $0.066~\text{fm}$ and $0.049~\text{fm}$. Employing Short Distance Factorization, we extract the pseudo-DA on the lattice for Ioffe times $\nu \leq 4.5$, and the various lattice spacings allow us to take the continuum limit. We employ a basis of Jacobi polynomials to parametrize the distribution amplitude, which allows to express the matching to the pseudo distribution in closed form, and we observe a strong effect which we attribute to the heavy charm-quark mass.Comment: Contribution to the 40th International Symposium on Lattice Field Theory (Lattice 2023), July 31st - August 4th, 2023. Fermi National Accelerator Laborator

B-meson spectroscopy in HQET at order 1/m

35 pages, 14 tables, 17 figures; Introduction extended and typos corrected. Version accepted for publication in PRDWe present a study of the B spectrum performed in the framework of Heavy Quark Effective Theory expanded to next-to-leading order in 1/m and non-perturbative in the strong coupling. Our analyses have been performed on Nf=2 lattice gauge field ensembles corresponding to three different lattice spacings and a wide range of pion masses. We obtain the Bs-meson mass and hyperfine splittings of the B- and Bs-mesons that are in good agreement with the experimental values and examine the mass difference m_{Bs}-m_B as a further cross-check of our previous estimate of the b-quark mass. We also report on the mass splitting between the first excited state and the ground state in the B and Bs systems

HQET at order 1/m1/m: II. Spectroscopy in the quenched approximation

Using Heavy Quark Effective Theory with non-perturbatively determined parameters in a quenched lattice calculation, we evaluate the splittings between the ground state and the first two radially excited states of the $B_s$ system at static order. We also determine the splitting between first excited and ground state, and between the $B_s^*$ and $B_s$ ground states to order $1/m_b$. The Generalized Eigenvalue Problem and the use of all-to-all propagators are important ingredients of our approach.Comment: (1+18) pages, 3 figures (4 pdf files); pdflatex; v2: corrections to table 1, results unaffecte